MLS superstar Lionel Messi trained on ​his own as defending World ‌Cup ​champion Argentina held its first practice session in the United States.

The Inter Miami captain has been dealing with muscle fatigue in his left hamstring ⁠since May 24 but is expected to be ready for Argentina's World Cup opener against Algeria ‌on June 16 in Kansas City.

Messi, 38, joined Argentina at its training ‌base in Kansas City and ‌worked on "specific exercises" on Monday ‌along with several ‌teammates who are also dealing with fitness concerns.

"The players ​who are ‌suffering ​from niggles and injuries ⁠continue to work with the physiotherapy team on specific exercises on the ​pitch ⁠and ⁠are making good progress," Argentina's Football Association said.

Argentina, ranked No. 3 in the ⁠FIFA/Coca-Cola world rankings, will play its final tune-up match against Iceland on June 9 in Auburn, Ala.

Messi, the two-time MLS MVP and eight-time ‌Ballon d'Or winner, is competing in his record ​sixth World Cup. The midfielder is Argentina's all-time leader in caps (198) and goals (116) since making his debut with ​the national ‌team in 2005.